More about walking

Air pollution-aware walking routes in west London

About this project

Poor air quality is harmful to health and the environment. It is estimated that current levels of air pollution reduce the life expectancy of everyone in the UK by an average of 8 months. West London experiences some of the worst air quality in the country.

Individual exposure to poor air quality can be managed by choosing walking routes away from the most polluted areas. In London these tend to be the busiest roads. Choosing to take a route which takes you away from busy roads will reduce exposure to the harmful pollutants and consequently have a beneficial effect on health.

The pollution maps are based upon air quality modelling produced by the Greater London Authority (GLA) using information contained in their London Atmospheric Emissions Inventory 2004 (LAEI 2004). The LAEI is a database of geo–referenced datasets of atmospheric emissions sources and information about the location, rates of emissions and estimates of the quantity of specific pollutants emitted into the air within and around the Greater London area. For further information see the London Atmospheric Emissions Inventory.

Calculating walking routes that avoid air pollution

For the purposes of this project we have used modelled concentration of nitrogen dioxide (NO2) from the LAEI.

The air pollution maps derived from the LAEI are overlaid on a map of the roads and paths in the West London Boroughs, and average levels of NO2 pollution along each road or path segment are calculated.

When calculating a ‘low pollution’ walking route we look at each road or path segment’s average NO2, and its length. We take these together as a measure of NO2 exposure along a segment. A route is chosen that minimises the overall exposure.

It is important to note that the pollution data we are using are modelled data. This means that a low-pollution walking route cannot be guaranteed to give the absolute minimum pollution exposure for a walking route between any two given points on any given day. A route is anticipated to be the lowest or amongst the lowest walking routes on an ‘average’ day.

If you are sensitive to poor air quality, and live or work in London, you may benefit from receiving free pollution alerts from the London airTEXT service. The alerts are sent to advise people when elevated pollution levels are forecast. To register please visit www.airtext.info

Project supporters

This project was made possible through the support of the West London Air Quality Cluster Group (comprising the London Boroughs of Brent, Ealing, Hammersmith & Fulham, Harrow, Hillingdon, Hounslow, and Richmond upon Thames) and a grant from TfL.